NEW YORK (Reuters Health) - The exercise that babies get while suckling at the breast may be an essential component of the respiratory benefits associated with breastfeeding, new research shows.
Dr. Ikechukwu U. Ogbuano of the University of South Carolina in Columbia and colleagues found that by 10 years old children who were breastfed for 4 months or longer had larger lung capacities than their counterparts who had been nursed for a shorter amount of time or not at all. The breastfed children were also able to expel air from their lungs more quickly.
While the children's speedier exhalations could have been related to the beneficial components of breast milk, "the lung capacity cannot be really explained by the immune factors in the breast milk," Ogbuano told Reuters Health. Instead, Ogbuano and his colleagues argue, the harder work required of babies who drink from the breast rather than a bottle is a more likely explanation.
Breastfeeding is known to help protect babies from developing respiratory infections, but studies of whether it may reduce their risk of asthma risk later in life have had mixed results, the researchers write in the journal Thorax. To investigate, they looked at lung function in 1,033 children who were 10 years old, born on the Isle of Wight, and were followed since birth.
The average lung capacity, as measured by the volume of air a child could exhale forcibly, was 54 milliliters greater in those who were breastfed for at least 4 months than in those who were not been breastfed at all. Peak expiratory flow, or the maximum speed at which the air can blown out of the lungs, was 180.8 milliliters per second faster in these children.
The lung function in children who had been breastfed for a shorter amount of time wasn't significantly different from the lung function of children who weren't breastfed at all.
Ogbuano and his team note that the pressure nursing babies exert on the breast before milk begins to flow is triple that required when drinking from a bottle; nursing sessions also last 8 minutes, on average, compared with 4.4 minutes for bottle feeding. Nursing four to eight times a day "may also help to prepare these children for a lifetime of physical fitness," Ogbuano said in an interview.
The findings suggest that babies who are bottle-fed with pumped breast milk may be missing out, Dr. Wilfried Karmaus, another researcher on the study, told Reuters Health. "We may go just in the wrong direction with the pumping and bottle feeding. That's why it's so important to really clearly consider what's going on there."
Karmaus noted that in Canada and Europe, generous maternity leave policies make it possible for women to directly breastfeed their infants for several months if they choose, while in the U.S. many women must return to work after only a few weeks. Giving U.S. women longer maternity leave might pay for itself in terms of health benefits, such as reductions in obesity, he suggested, calling for an economic analysis to address the issue.
SOURCE: Thorax, November 2008.